1. Field of the Invention
The present invention relates to a pattern-forming material and a pattern-forming method, and particularly to a conductive pattern-forming material by which a fine conductive pattern can be readily formed and which is useful for forming a fine wiring substrate, and to a method for forming a pattern using the conductive pattern-forming material.
2. Description of the Related Art
Conventionally, various conductive pattern-forming materials have been used for formation of wiring substrates and the like. A typical pattern-forming method is one in which thin film conductive material formed by a well-known method such as vacuum deposition is provided on an insulator and subjected to resist treatment. A portion of the previously-prepared resist is removed by pattern exposure, and thereafter, subjected to etching to form a desired pattern. This method requires at least four processes. When wet etching is carried out, a process for the disposal of waste liquid is additionally required. Therefore, the aforementioned method is inevitably complicated.
Further, there is also another known pattern-forming method in which a conductive pattern-forming material uses photoresist. This is a method in which a base material coated with photoresist polymer or having dry film-shaped photoresist applied thereon is subjected to UV exposure via an arbitrary photo mask to form a lattice-type pattern or the like. This method is useful for the formation of an electromagnetic-wave shield as it requires a high conductivity.
With advances in the development of micro-machines, and with super LSIs being made even smaller in recent years, the very fine wiring structure of a nano-scale has come to be demanded. There is a limit to making microstructures by conventional metal etching, and there is a fear of the thin-line portion being broken during processing. For this reason, a method using a functional organic molecular thin film has been proposed in order to form an orientation-controlled fine pattern. However, in this method as well, imagewise writing is carried out by UV exposure using a conventional mask such as a lithographic film, and so, the degree of freedom in the formation of circuits is not very high.
Recently a new method has been given attention where a liquid material is supplied onto a substrate and a pattern is directly formed thereon. This method is used for the production of organic transistors. They are produced as follows. First, a separator of polyimide is formed on an insulating substrate using photolithography, and the surface is subjected to water repellent finishing using plasma processing. Subsequently, a conductive high polymer solution for forming a source electrode and a drain electrode is supplied by an ink jet device in an imagewise manner to thereby form the electrodes. Thereafter, a semiconductor layer material and an insulating layer material are sequentially spin coated to form a semiconductor layer and an insulating layer. Finally, a gate electrode is formed by an ink jet device in an imagewise manner.
Such a production method of organic transistors is also disclosed in, for example, Japanese Patent Application Laid-Open (JP-A) Nos. 11-204529, 11-207959 and 2000-208774. This method has the advantage that no large-scale apparatus such as a vacuum evaporator is required for the formation of electrodes. However, regions for isolating electrodes formed adjacently is carried out by conventional photolithography. This restricts the accuracy of electrode formation. The complicatedness of the photolithographic process has not been solved.
In recent years, a method using a conductive pattern-forming material has been given attention where a pattern is formed directly from digitized data without a mask. Various pattern-forming methods have been proposed.
Such a method for forming a digitized pattern can be expected to result in a fine pattern arbitrarily formed. One such method uses a self-organizing monomolecular film. This method uses a molecular aggregate which is spontaneously formed when a substrate is immersed in an organic solvent containing a surface active molecule. By employing a molecular aggregate such as a combination of an organic silane compound and SiO2, Al2O3 or a substrate, or a combination of alcohol or amine and a platinum substrate, the formation of a pattern by photolithography is made possible. Although this monomolecular film enables the formation of a fine pattern, it necessitates the used limited combination of substrate and material. Therefore, bringing the development of the method to practical application is difficult, and so under the existing circumstances, a pattern-forming technique for fine wiring which is suitable for practical use has not yet been established.